Bolt



J. Hl SHARP Dec. 10,

BOLT

Filed May 4, 1931 /JO I I .Patented Dec. l0, 1935 UNITED. s'rATlazs PATENT OFFICE BoL'r John H. Sharp, Chicago, Ill. 'Application May 4, 1931, serial No. 534,962

is claims. (ci. s1i

5 ularly to such for fastening the wood part of a railway freight car to the metal frame.

The principal object of my invention, generally considered, is the provision of bolts, particularly adapted for connecting wood sheathing, lining,

' 10 roofs, running boards and floors to metal or wood framing, and which, when in place, lie in fluidtight relation With the wood to thereby prevent the entry of moisture into the bolt hole along the shank of the bolt, s that rotting of the wood and l5 other undesirable results are avoided.

Another object of my invention is the provision of a bolt particularly adapted for connecting wood and like compressible material to metal rparts, which bolt may be used with such parts after the same have merely been drilled or apertured for receiving the minimum section of the bolt with the desired slight clearance, said bolt, when in place,l having threaded itself into such tight engagement that those portions of the wood surrounding theY bolt shank have been put under pressure, forcing them into all voids, to such an extent that the most extreme shrinkage or warp- 'age of the wood will not relieve the holding pressure sufficiently to admit moisture, whereby the bolt opening' is sealed against ,the entrance of f Water and air, so that not only isrotting of the wood minimized, but the entrance of warm air, for example, into refrigerator cars. is prevented.

Another object of my invention is the provision of a bolt with an intermediate portion of the shank tapered and specially threaded,v or formed with spiral iiutes and corresponding ribs therebetween, to adjacent the head so. that it will form corresponding ribs and flutes onva wood part to be connected thereby when driven into plate, as with a hammer, or spiral itself into the wod when the nut is applied, thereby automatically holding the bolt from turning during such nut application.

A still further object of my invention is the provision of a bolt particularly adapted for connecting Wood and metal parts, which bolt preferably has a head, the outer surface of which is approximately iiat or slightly' convex at the pe- 15o riphery, and the inner-surface of which is def'sirably slightly concave, and the shank itself then tapers a material distance toward the other end of the bolt, said tapered portion being formed with spiral utes adapted to engage wood and g5 disposed on such a steep pitch that axial pressure on the bolt will cause the same to spiral itlf into a pieceof wood after ithas been applied in an aperture therein, the'end of said bolt away from the head being threaded to receive an associated nut, the threads for the nut and'thevutes for 5 engaging the wood winding in opposite directions so that when the nut is applied, the spiral ilutes in the wood will automatically tighten themselves therein s o as to .finally prevent turning of the bolt and-permit a tight application of the nut. 10

Other objects and advantages of the invention relating to the particular arrangement and construction of the various parts will become apparent as the description proceeds.

lReferring to the drawing illustrating my in- 15 vention, the scope whereof is defined by the appended claims:-

Figure 1 is a side elevation of a bolt embodying my invention. i f

Fig. 2 is a fragmentary view, in transverse sec- 20 tion, of wooden sheathing and an associated metal frame portion with a preferred form of my bolt, shown in side elevation. used for connecting said wood and metal parts.

Fig. 3 isa view similar to Fig. 2, but showing the 25 sheathing after the bolt has been removed.

In connecting wood and metal structural members such as parts of railway vehicles, it has been customary to use bolts commonly designated as .carriage bolts with heads. the outer surfaces 30 of which are generally spherical, and the inner surfaces of which are plane, with the shank of the bolt adiacent the head generally square'or non-circular in section to turning ofy thebolt when the nut is applied t the other end. 35 When such bolts are employed with the head engaging the adjacent surfacej'of the wood, either said head projects beyond the surface of the Wood, or it is necessary to countersink the wood to receive the head so that the outer surface thereof 40 may lie normally flush with the surface of the wood. In either event, the bolt shank requires a bigger hole in the woodY than its outsidediameter,

`nut receiving threads on the other end of the bolt, so as to permit drawing or driving the bolt into the wood, without splitting it, until the head is normally substantially flush withthe corresponding surface of the wood, thereby eliminat- 5 ing, without countersinking, the damage and inconvenience frequently caused by protruding bolt heads. The flutes adjacent the bolt head are preferably formed of relatively steep pitch and so constructed thatthey arel adapted to formv -eective corrugations or ribs in wood, and on account of their being disposed onl the tapered portion ofthe shank, they will thread and wedge themselves into the wood to provide an airand water-tight joint. Referring now to the drawing in detail, like parts being designated by like reference characters, there is shown, as one embodiment ofmy invention, a bolt I which, in Fig. 2, is represented as connectingwooden sheathing 2 to a portion of a metal car framey 3. as by extending through registering apertures I in the sheathing and 5 in the frame. The end or shank 6 of the bolt7 protruding beyond the frame 3, through which it desirably extends loosely, has applied thereto Y a nut 1, which nut, when screwed tight on the threaded end portion II of the bolt, desirably forces the head 8, the outer surface of. which is convex or substantially fiat, into the wood 2 until it is substantially flush with the outer surface of 3Q said wood..

In order to make an air- -and water-tight joint with the wood' 2 and at the same time prevent turning of the bolt when the nut 1 is applied thereto, I preferably make the hole I in the wood of a diameter corresponding with that of the near said head to a diameter slightly greater, for

example, .050 greater than the normal diameter of said shank. On the outer surface of said tapering `or'frusto-conical portion, I apply ribs or threads l, separatedl by corresponding flutes or valleys. disposed on a relatively great pitch y and of coarse formation or widely spaced, preferably with sharp crests, and roots formed on a relatively easy curvature, so that Vwhen the bolt is driven or drawn into the wood, it will form cooperating wood flutes which will be interspaced with the bolt flutes to form a waterand'airtight joint between the shank of the bolt and the wood along the' aperture therein. las shown in Figs. 1 and 2, the diameter of the small end of the tapered portion at the base of the flutes is desirably slightly greater than the diameter of the threaded end at the crest of the threads.

To further enhance the waterproof construc- V tion, I desirably form the inner surface I0 of the bolt head 8 c'oncave, so that when th bolt is drawn tight into the wood, the periphery of the head will compress the fibers of the wood beneath tro nood, as shown most o1ear1y m Fig. 2. A1f the Il for receiving the nut 1 is Aright-handed,

the spiral ribs 9 for engaging the wood are formed lftinanded, that is the ribs s wind around the Abolt in-a direction opposite to that of the thread -I I, so that upon turning the nut tight, and thereby causing the bolt to turn with the nut, said bolt 'zowill tend to sph-nasen into the wood, ond whenA the head 8 is pressed into said wood so that' the outer surface 'thereof is substantially flush with, the corresponding surface of the wood, rotation will be stopped and the nut .maybe tightened 75.1 to the desired extent. in

the wood and the shankof the bolt.

In applying such an improved bolt, the aper ture 4 in'the wood is desirably made to correspond in size with the outer or normal diameter of the end having the threads I I, 'that is, of a size corresponding'with the normal size of the 5 shank 6, desirably with the lusual clearance, so that when the tapered portion of the shank having the ribs 9 thereon engages the apertured portion 4 in the wood, the wood is not only iluted without any tearing action, but the aperture is 10 expanded to correspond with the increasing tapered portion of the bolt. In this way, the bolt, is not only forced into tight engagement with the wood to prevent turning of the bolt, but the Wood is compressed around the bolt with a pres- 15 sure greater than any relief that can be obtained by drying the' wood out, so that whether the wood is wet or dry the bolt is always under pressure to exclude air and moisture from between At the 2;) Vsame time, the head is drawn to a position preferably substantially flush with the adjacent surface of the wood, the pitch of the ribs 9 being such that the bolt may be started, and driven home, if desired,`by hammering or otherwise 2., forcing it into position in the wood.

Fromthe foregoing, it will be seen that I have devised a bolt particularly adapted for connecting wood and metal, although it is not limited to such use. Bolts such as havev been described are designed more particularly for use on railway freight cars. On such equipment, bolts are used to fasten the wood parts, such as lining or sheathing, to the wood or metal frame of the car. In' order to provide a smooth surface which 3.;

has no projections to interfere with or injure vthe lading,.such bolts are usually applied with increase in size as the wood dries and seasons in service. This has been found true -of every type of straight and tapered shank bolt previously used in such car construction, even where bolts were driven through undersize holes because they 5o had to tear the hole larger than the bolt shank in order to pass through the wood. In the present invention, by providing a bolt shank tapered and equipped with self-threading left-hand spiral flutes, I eliminate thel space between the bolt 5 shank and the wooden part, thereby obviating the entrance of air and moisture with ensuing deterioration and rotting of the wood.

When in use, the spiral self-threading lefthand diluted and tapered portion draws itself 60 into the wood with a rotary motion, the increasing diameter of the tapered ribs acting to compress the wood fiber, filling all voids between the sides of the bolt hole and the metal of the bolt shanlr'thereby forming a seal which prevents e5 the entrance of moisture into the bolt-opening, prevents leaking into thecar, and rotting of the wood fiber. Inasmuch'as the amount of com`- pression is greater than the possible shrinkage, no leaks can dey: op when the wood shrinks or dries out. y a The left-hand flutes onf'the tapered shank being opposed `to the `right-hand thread made ltov receive the nut, Ypull/the bolt more tightly into the wood when the nut is tightened on the bolt, v

vcuts a groove for itself in the wood fiber, and

the head is eventually drawn in substantially flush with thel wood surface,- .thereby eliminating the necessity for countersinking. This action does not tear the wood fibers or cause them to stick-up with a consequent liability to 'damage the lading.

Although I have shown as an illustrationthe bolt applied to the side sheathing of a box-car, it will be understood that such bolts can be used to advantage in numerous other relations, such as in the floors and roofs of freight cars, for holding automobile bodies on the frame, and, generally, wherever it is desired to bolt wood to metal. My bolt, which is preferably formed of f metal, is adapted for use with self-locking or grip nuts as well as common nuts.

Although a preferred embodiment of my invention has been illustrated, it will be understood that modifications may be made without departing from the scope of the appended claims,

I claim:

l. A rigid metal bolt adapted for use in wood and provided with a head at one end, a standard exterior screw thread on the other end portion for engaging a nut, and a reversely taper iiuted Vshank between said head and threaded portion,

which spirals itself into the wood when the nut is tightened on the standard screw thread.

2. A rigid metal bolt provided with a head, a standard exterior screw thread on one end portion for engaging a nut and a taper threaded shank portion between said head and threaded portion to engage a wooden part held by the bolt as a means of excluding moisture from the bolt hole to eliminate rotting of the wood adjacent to said bolt hole.

3. A headed bolt provided with a standard external screw thread, a shank with tapered spiral flutes between its head and thread so as to screw itself into wood upon the application of axial pressure, forcing the wood into all voids between the solid portion of the said bolt shank and the sides of the bolt hole, thus closing the hole against the passage of moisture and air.

4. A rigid metal bolt comprising a shank and a head on one end thereof, that portion of the shank adjacent the head being tapered and having widely spaced flutes of relatively large pitch adapted to engageV wood, and the end of the shank away from the head being externally threaded to engage a nut.

5. A bolt comprising a shank and an approxi-l mately flat head on one end thereof, that portion of the shank adjacent the head being tapered to a smaller cross-section away from said head and formed with spiral iiutes, the opposite end of said shank being externally threaded in the opposite direction for engaging a nut.

6. In combination, apiece of metal, a piece of wood, a bolt passing loosely through an aperture in said metal and tightly through a registering aperture in said wood for joining them together, that portion of the bolt in the Wood involving a tapered shank adjacent an approximately iiat he'ad and-formed with iiutes on such a steep pitch that the bolt may be driven or drawn into place, the outer surface of said head being normally approximately ush with the adjacent surface of the wood, and the fluted portion of said shank being tightly engaged with said Wood and lying in ,Huid-tight relation 5 therewith, the end of said bolt extending through the metal being threaded for receiving a nut.

7. The combination of wood and metal, and A means connecting them in superimposed relation' comprising a bolt and a nut, said bolt having a shank headed at one end and gradually tapered to a right-handed threaded portion ald-A jacent the other end lfor receiving the nut, said tapered portion having left-handed spaced flutes applied thereto anddisposed in tight engagement with the wood, said iiutes having a relatively steep pitch, and the threaded portion passing loosely through the metal and the nut applied thereto and screwed tight, whereby the bolt will spiral itself into thelwood into fluidtight engagement therewith. 8. A bolt of` the kind described consisting of a shank having a head at one end and threaded for a generally cylindrical portion of its length at the opposite end, the shank intermediate the head and threaded portion being of greater diameter than the threaded portion of the shank at the crest of the threads and tapered from the head end toward the threaded end, said tapered portion having flutes thereon extending spirally lengthwise of the shank and in the opposite direction to the threads at the end ofthe shank.

9. A two-part separable fastener consisting of a nut and a bolt, the shank of which is provided withl a head and has an externally threaded end portion on and off which the nut may be screwed, characterized in that a portion of the bolt shank between its head and threaded end portion is tapered and provided with a pluralty of bolt-hcle-wall engaging ribs stepped therearound and each projecting farther'from the shank axis than the shank thread'andalso lying in a helical path of which the direction of .winding is reverse to that of the shank thread.

10. A two-part separable fastener consisting of a nut and a bolt, for connecting pieces provided with bolt holes, the shank of said bolt being provided with a head and ,an externally screwthreaded end portion on and off which the nut may be screwed, characterized in that a portion of the bolt shank between its head and threaded end portion is tapered andprovided With a plurality of bolt-hole-wall .gripping ribs stepped therearound, each projecting farther from the shank axis than the threads, and each lying in a helical path of which the direction of winding is reverse to that of the shank threads, said ribs initially having an outside diameter greater than the diameter dof a bolt-hole in one of said pieces, y

so as to be finally positioned, in friction gripping relation with the wall defining said hole, by forciblev axial insertion to cause the material of one of thefengaged surfaces tojaccommodate itself to the other, resulting in a tight lit of the bolt in the G5 hole, with a rib gripping action increasing with an increase of the torque applied to the shank by the nut, during subsequent screwingup of said nut upon the bolt to tightly clamp the pieces be# tween the head and the nut.

. 11. In combination with a plurality/of juxtaposed parts provided with bolt holes, a two-part separable fastener consisting of a nut and a bolt, the shank of said bolt being disposed in said holes for connecting said parts and provided with a head and an externally screw-threaded end portion on. and off which the nut may bescrewed, characterized in that a portion of the bolt shank between its head and threaded end portion is 5 tapered and provided with a plurality of bolthole-wall gripping ribs stepped therearound, each projecting farther from the shank axis than the threads, ,and extending substantially the entire distance from the head to the threaded end porlq tion, said rib's initially having an outside diameter greater than the diameter` of a bolt-hole and being finally positioned, .in friction gripping relation with the wall of a part defining said hole, by forcible'axial insertion to cause the material of self to the other, resulting in a tight iit of the bolt in the hole, with a rib gripping action in-l creasing with an increase of the'torque applied 'to the shank by the nut, during subsequent screwy ing up of said nut upon the boltrto tightly clamp the fastened parts between 'the head and the nut.

v12. In combination with a plurality of juxtaposed parts provided with bolt holes, a two-part separable' fastener consisting of a nut and a bolt;

, characterized in that a portion of the bolt shankv 30 between its head and threaded end portion is tapered and provided with a plurality of bolt-holewall gripping ribs stepped therearound, leach proiecting farther from the shank axis than the threads, and eachlying in a helical path of which the direction of winding is reverse to that of the shankv threads, said ribs initially having an outside ldiameter greater than the diameter of a bolt-hole. and` being finally positioned, in friction gripping relation with the wall of a part definingl said hole, byforcible axial .insertion to cause thenmaterial of one of the engaged surfaces to accommodate itself to the other, resu1t. ing in a tight iit of thebolt in the hole, with a rib gripping'action increasing'with an increase 510i the torque applied tothe shank'by the nut,

during subsequent screwing'up of said nut upon the bolt to tightly clamp the fastened parts betweentheheadandthe nut.

i3. In combination with a plurality of juxta- A ,ml posed parte provided-with belt holes. e two-pm separable fastener consisting of a nut and a bolt, the shank of said boltbeing disposed in said holes for connecting `said partsl and provided. with `a 1head'and a screw-threaded end portion on and off which the n'ut may be' screwed, characterized inthat a portion of the bolt shank between its head and threadedjend portion isprovided with a plurality of bolt-hole'fwall gripping ribs stepped therearound, eachprojecting farther from the shank axis than the threads, and each lying in a helical .path of which the direction ofwinding is-reverse to/th'at of the shank threads, the pitch of 'said ribsbeing -steep like that of the threads of a drive screw to facilitate application,v said ribs 65. initiaily having anoutside diameter greater than the diameter of a bolt-hole andjbeing 1111811? positloned, in friction gripping relation with the wall' of a -part deiining said'f hole, by mere axial force applied to the bolt to cause the material of one ofthe engaged surfaces to be tapered to accommodate itself to'the other, resulting in a tight fit of the bolt in the hole, with a rib gripping action increasing with an increase of the torque applied .to the shankl by the nut, during one of the engaged surfaces to accommodate it- :said iin being adapted to grip the sides of Athe subsequent screwing up of said nut upon the acuoso a belt te muy clamp the fastened parte between projecting farther from ythe shank axis than the 'bolt in a bolt-hole' and initially having'the outside diameter of its main portion greater than 20 the diameter of a bolt-holein one of said pieces, so as to'be finally pomtioned, in friction gripping relation with the wall I defining said hole, by forcible axial insertion to cause the material of one of the engaged smfaces to accommodate itself` to the other, resulting in a tight flt of the bolt in the hole, with a rib gripping action increasing with an increase of the torque applied to the shank by the unut, during vsubsequent screwing up of said nut upon the bolt to tightly clamp the piecesbetween the head and the nut. 15. A bolt comprising a shank, a head, and an annular flange on'the inner face of the head and adapted to sink into an associated member provided with a hole receiving said bolt to forni 35,

" a seal to prevent leakage of liquid beneath the ing substantially the full length of said enlarged persen and adapted te grip the sides er the bolt-hole, to resist turning of lsaid bolt when Y' an associated nut is tightened on said threaded portion.

16. A bolt comprising a shank, 'and a thin disc- 'like head, said shank having the portion remote -from said head externallythreaded to receive a nut, and that portion between said threaded portion andhead formed with a integral with said shank and head and extending along said shank, on a taper, in a steep generally helical path, toward the peripheral portion of said head,

bolt-hole to resist turning of said boltwhenan associated nut is tightened on' said threaded portion. v

17. A bolt-'comprising a shank, a head, and an annular edge portion extending at' an angle to the transverse plane of said head, toward the end of said shank away from said head, and

' adapted to sink into an associated member provided with a holreceiving said bolt to form yaseal Atoprevent leakage of liquid beneath theheadkinto said bolt-hole, said shank the portion remote from said head threaded to re-A ceive a nut` and that portion b/etween' said threaded portion and head enlarged-toa diameter greater lthan said threaded portion and formed with splralribs adapted to grip theportions of the member denning said hole to resist` turning of said ybolt when an associated nut is tightened on said threaded portion. s

nut and that portion between said threaded portion and head tapered to a. diameter greater `than said threaded portion and formed with spiral iiutes adapted to grip the surface of said member deiining said hole to resist turning of said bolt when an associatednut is tightened on said threaded portion.

, JOHN H. SHARP.. 

